1. Field of the Invention
This invention relates to a radiation image read-out and reproducing apparatus for use in a radiation image recording and reproducing system, wherein read-out and reproduction of a radiation image are carried out by use of the same scanning system in the same apparatus.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to a radiation passing through an object such as the human body to have a radiation image of the object stored thereon, and is then scanned with stimulating rays such as a laser beam which cause it to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to electric image signals, and the radiation image of the object is reproduced as a visible image by use of the image signals on a recording material such as a photographic film, a display device such as a cathode ray tube (CRT), or the like.
In the aforesaid radiation image recording and reproducing system, the stimulable phosphor sheet is used to temporarily store a radiation image until the sheet is scanned with stimulating rays to read out the radiation image. Therefore, after the radiation image is read out from the stimulable phosphor sheet, radiation energy remaining thereon should be erased for reusing the stimulable phosphor sheet.
The aforesaid radiation image recording and reproducing system has heretofore been composed of a recording apparatus for storing a radiation image on a stimulable phosphor sheet, a radiation image read-out apparatus for reading out the radiation image stored on the stimulable phosphor sheet and generating image signals, and an image reproducing apparatus for reproducing a visible radiation image by, for example, scanning a light beam modulated in accordance with the image signals on a recording sheet and recording the visible radiation image on the recording sheet. Therefore, in order to form the final visible image of the radiation image, which was stored on the stimulable phosphor sheet, on the recording sheet in the conventional radiation image recording and reproducing system, it is necessary to provide two independent apparatuses, i.e. the read-out apparatus for reading out the radiation image from the stimulable phosphor sheet and the reproducing apparatus for reproducing the radiation image on the recording sheet, besides the recording apparatus.
In recent years, various attempts have been made to make small the aforesaid radiation image recording and reproducing system as a whole and to reduce the manufacture cost of the system. However, with the conventional radiation image recording and reproducing system, the read-out apparatus and the reproducing apparatus must be provided independently of each other as mentioned above, and the system as a whole cannot be made so small. Also, a scanning system and other components must be provided independently in each of the read-out apparatus and the reproducing apparatus, and therefore the manufacture cost of the radiation image recording and reproducing system cannot be reduced markedly.
Though an X-ray image read-out and reproducing apparatus wherein the same light source is utilized for read-out and reproduction, and read-out and reproduction are carried out alternately in the same stage is proposed in Japanese Unexamined Patent Publication No. 58(1983)-184677, only a conceptual view of the apparatus is shown in the specification thereof and no concrete configuration of the apparatus is described therein. Therefore, it is not always possible to put such an apparatus into practice. Also, with the proposed apparatus, scanning is carried out by moving the light source and a photodetector with respect to a sheet. With such a scanning method, the movement mechanism becomes complicated and it is not always possible to achieve quick scanning. Further, with the proposed apparatus wherein a light modulator and the photodetector are moved by a drive mechanism into and out of an optical path in the course of change-over of the apparatus between read-out and reproduction, the apparatus is rendered complicated also by the drive mechanism.